Method of Estimating the Volumetric Carrying Capacity of a Truck Body

ABSTRACT

A method for estimating the effective volumetric capacity of a truck body includes establishing a side-to-side profile of a generic load model by extending load side lines upward at a predetermined material angle of repose from the upper edge of the side walls of the truck body and a front-to-rear profile by extending a front load line upward from the upper edge of the front wall and a rear load line upward from at or near a rear edge of the floor at the predetermined material angle of repose. Load plateau lines having predetermined dimensions are established and the height of the plateau lines is determined. A top profile of the generic load is then created and the shape of the load plateau is adjusted into a closed curve shape. A final three-dimensional generic load model is formed and the volume of load model is calculated.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This patent application claims the benefit of U.S. Provisional PatentApplication No. 60/336,064, filed Nov. 2, 2002.

FIELD OF THE INVENTION

This invention relates generally to off-highway trucks and moreparticularly to a method of calculating the estimated volumetriccarrying capacity of the body of an off-highway truck.

BACKGROUND OF THE INVENTION

In mining and construction environments, off-highway trucks are used tohaul a variety of different materials such as, for example, coal, rock,ore and overburden materials (i.e. the material overlying ore/coaldeposits). Such off-highway trucks generally comprise a truck chassis orframe, which supports a truck body for receiving and carrying a load.

The carrying capacity of a truck is defined by two parameters: theweight or load carrying capacity of the truck and the volumetriccarrying capacity of the truck body. These two parameters must besynchronized with the density of the material to be carried by the truckto ensure that the truck is properly utilized. If not, the truck can beoperating either under capacity, i.e. short in payload, or overcapacity, i.e. with a heavier than desired payload.

The truck manufacturer defines the weight carrying capacity of anoff-highway truck. For a given haulage application, dividing the truckweight carrying capacity by the density of the material to be carriedyields the required optimal volumetric carrying capacity for the truckbody in that application.

Presently, off-highway truck manufacturers provide a volumetric capacityrating for their truck bodies that is presently based on the Society ofAutomotive Engineers (SAE) Standard SAE J1363 (January 1985, reaffirmedNovember 1995) (“the SAE standard”). Unfortunately, however, this SAEstandard does not provide a very accurate estimate of the actualvolumetric carrying capacity of a truck body.

The SAE standard rates the volumetric capacity of a truck body both instruck and heaped volumetric capacities. The sum of its struck volumeand its 2:1 heap above the struck volume/struck line is its 2:1 heapedvolume. Under the SAE standard, the struck volume of large off-highwaytruck dump bodies is based on an assumed struck load which extendsupward from the rear edge of the floor of the truck body (on open endedtruck bodies) at a 1:1 slope (corresponding to a material angle ofrepose of 45 degrees) to the top edge of the side walls of the body. Theheaped volume is based on an assumed load heap defined by the truck bodysides and the line defined by the intersection of the rear struck lineand the body sides and extends upwards at a 2:1 slope (corresponding toan angle of repose of 26.6 degrees).

There are major dimensional problems with the SAE 2:1 heaped volumetricrating methodology set forth in the SAE standard. First, with respect tothe struck volume calculation, there are very few materials that willstand at a 1:1 slope in a static condition let alone in a dynamiccondition, i.e. when the truck is moving. Second, the heaped volumecalculation is based on a different slope or material angle of reposethan is used in calculating the struck volume. Thus, the SAE standardessentially assumes a load that does not have a constant material angleof repose, i.e. a load wherein the angle of repose of the load materialat the rear of the truck body changes from 45 degrees to 26.6 degreesabove the side walls of the truck body. In the real world, eachparticular side of a load heap carried in a truck body nearly always hasa substantially constant angle of repose. However, it should be noted,that each side of a load heap, i.e. front, back, left and right may notalways have the same angle of repose.

The third major problem with the methodology of the SAE standard is thatit attempts to define the load heap by a series of four flat planes,which together resemble the roof of a house. In actuality, load heapscarried in truck bodies have a configuration that is more conical inshape.

Accordingly, the methodology of the SAE standard is based on a loadmodel that is different in several critical respects from the actualreal world configuration of a load carried by a truck body. As a result,the SAE standard produces a truck body volumetric capacity rating dratdoes not accurately reflect the actual achievable volumetric carryingcapacity of a truck body. In fact, the SAE standard consistentlyoverrates the volumetric carrying capacity of a truck body. This isrecognized in certain South American countries where the practice is to“de-rate” the SAE standard volumetric capacity of a truck body to 85% ofthe volumetric rating produced by the SAE standard. This method,however, also provides little more than a rough estimate of the actualvolumetric carrying capacity of a truck body.

Since the SAE standard substantially overrates the actual volumetricweight carrying capacity of a truck body, off-highway truck userstypically are unable to achieve the full load-carrying capabilities oftheir truck. Moreover, attempts to match the effective volumetriccarrying capacity of a truck body with the materials being hauled andthe weight carrying capacity of the truck so as to achieve full payloadutilization of the truck amount to little more than guesswork because ofthe inaccuracy of the SAE standard. Accordingly, a need exists for amethod to accurately estimate the effective volumetric carrying capacityof a truck body.

BRIEF SUMMARY OF THE INVENTION

The invention provides a method for rating or estimating the effectivevolumetric carrying capacity of a truck body. The method includes a StepA where a side-to-side profile of a generic load model is established byextending load side lines upward at a predetermined material angle ofrepose from the upper edge of each of the side walls of the truck body.In Step B, a front-to-rear profile of the generic load model isestablished by extending a front load line upward from the upper edge ofthe front wall of the truck body at the predetermined material angle ofrepose and a rear load line upward from at or near a rear edge of thefloor of the truck body at the predetermined material angle of repose.Step C consists of defining a load plateau plane having predetermineddimensions in the front-to-rear and side-to-side profiles anddetermining the height of the load plateau plane. In Step D, the topprofile of the generic load is then created from the side-to-side andfront-to-rear profiles and the shape of the load plateau is thenadjusted into a closed curve shape. In step E, the front, rear and sideload lines below the final outer boundary of the load plateau arecontoured into a generally conically shaped surface in which the sidesof the conically shaped surface are inclined at the predeterminedmaterial angle of repose. This forms a final three-dimensional genericload model defined by the load plateau and where the generally conicallyshaped surface intersects the side wails, front wall and floor of thetruck body. In Step F, the volume of the final three-dimensional genericload model is calculated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an exemplary off-highway truck having a truckbody the capacity of which can be rated using the method of the presentinvention.

FIG. 2 is a rear view of the off-highway truck of FIG. 1.

FIG. 2 a is a diagram representing exemplary material angles of reposewith corresponding material slopes of 2.2:1-1.4:1.

FIG. 3 is an end view of the truck body showing a step in establishing aside-to-side profile of a generic load in accordance with the presentinvention.

FIG. 4 is an end view of the truck body showing a further step inestablishing the side-to-side profile of the generic load that includesestablishing a side-to-side profile of the load plateau plane.

FIG. 5 is a side view of the truck body showing a step establishing afront-to-rear profile of the generic load.

FIG. 6 is a side view of the truck body showing a further step inestablishing the front-to-rear profile of the generic load that includesestablishing a front-to-rear profile of the load plateau plane.

FIG. 7 is a side view of the truck body showing the difference in heightbetween the front-to-rear profile of the load plateau plane and theside-to-side profile of the load plateau plane.

FIG. 8 is a side view of the truck body showing the final front-to-rearprofile of the generic load.

FIG. 9 is an end view of the truck body showing the final side-to-sideprofile of the generic load.

FIG. 10 is a top view of the truck body and generic load showing how theload plateau plane is transformed into a generally circular or ovalshaped load plateau.

FIG. 11 is a top view of the truck body and the generic load showing howthe load plateau can be divided into pie-shaped segments.

FIG. 12 is a perspective view of the truck body and the generic loadshowing how the load profile lines are extended from the load plateau tothe inside surface of the truck body.

FIG. 13 is a perspective view of the truck body and the generic loadmodel showing how the lines of contact between the generic load and theinside surface of the truck body are defined.

FIG. 14 is a perspective view of the truck body and the generic loadmodel.

FIGS. 15 a, b, and c are comparison diagrams showing the differencebetween the truck body volumetric capacity rating as calculated inaccordance with the present invention (FIG. 15 a) and the rating basedon a true 2:1 heap (FIG. 15 b) and the SAE volumetric capacity rating(FIG. 15 c).

FIG. 16 is a perspective view of a truck body having sideboards showinghow the addition of the sideboards affect the volumetric carryingcapacity rating of the truck body as calculated according to the presentinvention.

FIG. 17 is a perspective view of a truck body having a tail extensionshowing how the addition of the tail extension affects the volumetriccarrying capacity rating of the truck body as calculated according tothe present invention.

DETAILED DESCRIPTION OF THE IN

Referring now more particularly to the drawings, there is shown in FIGS.1 and 2 an exemplary off-highway truck 10 having a body 12 thevolumetric capacity of which can be rated according to the method of thepresent invention. The truck 10 includes a chassis 14 to which the body12 is attached. The chassis 14, in turn, is supported by a plurality oftires 16. The truck body 12 is generally constructed of steel panelswhich define the shape of the body 12 and beams which form thestructural framework for the body 12. The truck body 12 comprises, inthis case, side walls 18, a front wall 20 or front slope and a floor 22.It will be appreciated, however, that the method of the presentinvention can be used on truck bodies having any suitable configuration.

In the illustrated embodiment, the truck 10 and truck body 12 aregenerally symmetrical about their longitudinal axes. Accordingly, aswill be appreciated, reference to plural elements where only one isshown indicates that a complementary element is disposed on the side ofthe truck not shown (e.g., side walls 18).

In accordance with the present invention, a method is provided for muchmore accurately calculating or rating the volumetric carrying capacityof a truck body. In particular, the method of the present inventionprovides a volumetric carrying capacity rating which much more closelyapproximates the actual achievable effective volumetric carryingcapacity of the truck body under real-life loading conditions than thevolumetric rating produced using the SAE standard methodology and othersimilar methodologies. Thus, the present invention allows off-highwaytruck end users to more easily evaluate and select truck bodies fortheir particular haulage application. This, in turn, leads to moreefficient truck utilization, i.e. trucks carrying loads more closelymatched to their volumetric and weight carrying capacity.

Step 1—Establishing the Material Angle of Repose

As a first step for determining an effective volumetric capacity ratingfor a particular truck body, the truck body 12 in the illustratedembodiment, an assumption has to be made with regard to the loadmaterial angle of repose α. Any suitable value can be used such asillustrated in FIG. 2 a. For example, in the illustrated embodiment, a26.6 degree angle of repose α, which corresponds to a 2:1 load heap, isused for the load heap “around” the truck body 12.

While a constant angle of repose α, is used in the illustratedembodiment for ease of calculation, different angles of repose for thefront, rear and sides of the load often occur. A method of designingtruck bodies that can include collecting specific angle of repose datafrom a specific site is disclosed in copending application Ser. No.09/333,379.

Similarly, the predetermined angle of repose α used in the method of thepresent invention can be based on observations of loads carried by truckbodies in the field. In such a case, the material angle of repose in thedynamic condition should be observed. Accordingly, the material angle ofrepose should be observed after the truck has been driven a reasonabledistance and the load has stabilized.

In order to provide standard uniformity in the volumetric capacityratings calculated according to the present invention, it may beadvantageous to use a standard material angle of repose α for allcalculations. Alternatively, a set of standard values may be employedwith each individual standard value corresponding to a particularapplication (e.g., coal mine, copper mine, iron mine, etc.). Thus, whenrating the volumetric capacity of a body for a particular application,the corresponding standard material angle of repose .alpha. for suchmaterial could be used. Typical angles of repose are indicated in FIG. 2a,

Step 2—Establishing Side-to-Side Profile of Generic Load

After establishing the material angle of repose α to be used, adimensional-dimensional model of a generic load 25 (FIGS. 8, 9, 10, 11,13, 14, 16, 17) carried by the truck body 12 is created. This genericload model 25 is preferably created using a three-dimensional solidscomputer aided design (CAD) system for ease of calculation. However, thepresent invention is not limited to being performed with CAD systems andcould be performed using other systems and methods. In the illustratedembodiment, the three-dimensional generic load model 25 is begun byeating an initial side-to-side profile 24 (FIG. 3) of the generic loadmodel 25. In particular, a load side line 26 is extended upward from theupper edge or upper inner edge of each of the side walls 18 at thepredetermined angle of repose α (e.g., 26.6 degrees) to a peak in themiddle using an end view of the body 12 as shown in FIG. 3.

In reality, material carried in a dump body is rarely loaded to aperfect peak, rather a horizontally extending plateau forms on the topof the heaped load. Thus, a side-to-side profile 28 (FIG. 4) of the loadplateau is next formed with a predetermined width WE in the side-to-sideprofile 24 of the generic load model 25 as shown in FIG. 4. In thiscase, the width WE of the side-to-side plateau profile line 28 is set at⅕.sup.th of the inside width of the truck body 12, however, any suitablevalue, i.e. ¼, ⅙, 1/7, ⅛, 1/9, can be used. In creating theside-to-sideplateau profile line 28, the side load lines 26 of the generic loadmodel 25 are maintained at the predetermined angle of repose α and theload peak is removed above the side-to-side plateau profile line 28,i.e. the line where the horizontal distance between the side load linesequals the predetermined width WE of the side-to-side plateau profileline 28.

Step 3—Establishing Front-to-Rear Profile of Generic Load

In the illustrated embodiment, as a next step, a front-to-rear profile30 (FIG. 6) of the generic load model 25 is produced. Specifically,using a side view of the truck body 12, a front load line 32 is extendedupward (FIG. 5) from the upper edge of the front body slope 20 at thepredetermined material angle of repose α as shown in FIG. 5. Similarly,a rear load line 34 is extended upward (FIG. 6) from the rear edge ofthe floor 22 of the truck body 12 at the predetermined angle of repose αuntil it intersects the front load plane 32 (shown in phantom in FIG.6). In order to take into account the possibility that loading of therear of the body 12 to a spill point is unacceptable because of thepossibility of spillage out of the rear end of the body onto a haulroad, the rear load line 34 can be extended upward from a point spaced adistance D (e.g., 6 inches) inward from the rear edge of the floor 22 asshown in FIG. 6.

After the front and rear load lines 32, 34 are established, afront-to-rear profile 36 of the load plateau is then created (FIG. 6)with a predetermined length LS on the peak of the intersecting front andrear load lines 32, 34 as shown in FIG. 6. In this case, thefront-to-rear plateau profile line 36 has a length LS equal to the widthWE used in creating the side-to-side plateau profile line 28 (i.e., thestep illustrated in FIG. 4). As in step 2, the angle of repose α is keptconstant in creating the front-to-rear plateau profile line 36.

Step 4—Determining Maximum Height of Generic Load Model

As a next step, the maximum height of the generic load model 25 isdetermined. This is accomplished by comparing the height HE of theside-to-side plateau profile line 28 and the height HS front-to-rearplateau profile line 36, such as shown in FIG. 7. Specifically, thefinal height HE (FIG. 8) of the generic load model 25 is set at thelower of the height HE of the side-to-side plateau profile line 28 andthe height HS of the front-to-rear plateau profile line 36 (assumingthat these two heights are different). The lower height is used becausethe height of an actual load in the body 12 will be limited by eitherthe length or width of the body (unless such as in ideal situations HSequals HE). For example, in the illustrated embodiment HE exceeds HS.The true height of an actual load will not reach HE because the body 12is not long enough at the chosen material angle of repose α to hold aload of that size.

Once the final height HF is determined, both the side-to-side andfront-to-rear plateau profiles 28, 36 are set at the final height HFabove the body sides 18 (FIGS. 8 and 9 respectively). In particular, theheight of the plateau line in the profile (front-to-rear orside-to-side) having the higher height above the body side 18 is loweredto the height of the lower plateau line. Thus, at this point, theplateau lines should be at the final height HF in both the side-to-sideand front-to-rear profiles 24, 30 of the generic load model 25 as shownin FIGS. 8 and 9. In the profile in which the height of the plateau linewas lowered, the plateau line will be longer than the predetermineddistance used to initially define the plateau WE will no longer equalLS) because the material angle of repose α of the side, front and rearload lines 26, 32, 34 remains constant.

Note that the plateau width WE should not be more than 20% larger thanthe original width established in Step 2. While load heaps can easilyrun the length of the body, load heaps running the width of the truckbody are seldom if ever achievable. If the plateau width WE does exceedthe original width by more than 20% it will indicate that the pointwhere the load contacts the body side walls 18 is below the top of theside walls 18 or that the angle of repose for the material running tothe body sides is less than that established in Step 1, i.e. the loadingtool has to artificially push material sideways to get material to reachthe top of the body side walls. When designing a body, this problem canbe corrected by lengthening the body in the front-to-rear view orprofile.

It will be appreciated that the steps 2 and 3 described above andillustrated in FIGS. 3-7 do not have to be performed in any particularorder so long as side-to-side and front-to-rear profiles 24, 30 of thegeneric load model 25 are established and the height and length of theload plateau lines are defined. For example, the front-to-rear profile30 of the generic load model 25 can be produced prior to theside-to-side profile 24.

Step 5—Defining Shape of Load Plateau

At this stage, the side, front and rear load lines 26, 32, 34 and theload plateau lines 28, 36 define the generic load model 25. In order tomore accurately reflect the shape of an actual load heap carried in atruck body 12, the generic load model 25 is next molded into a moreconical shape. In the illustrated embodiment, his is accomplished byfirst creating a top load plateau profile 40 which in most cases will beoblong in nature though it could also be round if HS and HE are the sameheight. As shown in FIG. 10, the load plateau as defined by theside-to-side and front-to-rear profile lines initially has a rectangularshape when viewed from the top (because WE no longer equals LS). To moreaccurately reflect the shape of an actual load plateau, this rectangularshape must be converted into a rounder oblong or oval shape. In thiscase, the final top load plateau profile 40 is produced by inscribing anoval or circle within the lines of the rectangle. This oval or circlebecomes the outer boundary of the load plateau 38.

Step 6—Contouring Generic Load to Produce a More Conical Shape

Using the oval shaped top profile 40 of the load plateau 38 as thestarting point, the side, front and rear load lines 26, 32, 34 of thegeneric load model 25 produced in creating the side-to-side andfront-to-rear profiles 24, 30 of the generic load model 25 are contouredso that the generic load model 25 more closely resembles a conicalshape. In this case, the oval shaped load plateau top profile 40 isdivided into a plurality of pie-shaped increments by boundary lines 42as shown in FIG. 11. The boundary lines 42 defining the pie shapedincrements are spaced at equal angular intervals. In the illustratedembodiment, the load plateau 38 is divided into thirty-six 10 degreepie-shaped segments. Since it is anticipated that an actual load will besymmetrical about the centerline of the body 12, the load plateau 38could be divided in increments 42 only to one side of the body 12 (e.g.,eighteen 10 degree increments). The opposite side of the generic loadmodel 25 would then be formed as a mirror image of the side divided intoincrements.

For each pie-shaped segment boundary line 42, a contour line 44 (FIG.12) is extended downward at the predetermined material angle of repose αfrom the edge of the oval-shaped plateau 38 perpendicular to the tangentline of the plateau 38 at that point until the contour line 44intersects the inside surface of the truck body 12 as shown in FIG. 12.To define the lines of contact between the generic load model 25 and thesidewalk 18, front slope, 20 and floor 22 of the body 12, the pointswhere the contour lines 44 contact the inside of the truck body 12 areconnected to form a series of contact lines segments 46 as shown in FIG.13. The upper surface of the load model 25 is then formed (FIG. 14) byextending a contour plane 48 between each adjacent pair of the contourlines 44 from the plateau to the respective body contact line segment46. These contour planes 48 shape the upper surface of the generic loadmodel 25 into a generally conical shape as shown in FIG. 14.

Step 7—Determine Volumetric Capacity Rating

The volume of the three-dimensional generic load model 25 is thencalculated. This volume represents the effective volumetric carryingcapacity of the truck body 12. The volume of the dimensional-dimensionalgeneric load model 25 is most easily calculated using a CAD system.However, it is conceivable that the volume could be calculated usingother methods.

An example of the significant difference between the effectivevolumetric capacity rating as calculated using the method of the presentinvention and the capacity rating calculated using conventional methodsis illustrated in FIGS. 15 a-c. In particular, three dimensionallyidentically sized truck bodies are illustrated in FIGS. 15 a-c. Theeffective volumetric capacity of the first truck body 50 (FIG. 15 a) hasbeen rated using the method of the present invention. The volumetriccapacity of the second truck body 52 (FIG. 15 b) has been rated based ona load model using only a 2:1 heap (i.e., where the 2:1 slope ismaintained from the floor edge at the rear of the body) and flat planes.Finally, the volumetric capacity of the third truck body 54 (FIG. 15 c)has been rated based on the method set forth in the SAE standard. As canbe seen from FIG. 15, the volumetric capacity rating produced using thepresent invention (FIG. 15 a) is approximately 18% less that the ratingproduced using the SAE standard (FIG. 15 e) and approximately 11% lessthan the rating produced using a true 2:1 heap (FIG. 15 b).

In order to maximize the volumetric load carrying capacity of a truckbody 12, the height of the side walls 18 and the length of the body 12must also be properly matched. This becomes evident when the method ofthe present invention is used to rate the volumetric carrying capacityof a truck body 12 which has been modified with sideboards 56 or a tailextension 58. For example, FIG. 16 illustrates a completed generic loadmodel 25 that has been produced using the method of the presentinvention for a truck body 12 having sideboards 56. The sideboards 56increase the height of the side walls 18 of the body 12, however, theycan not be fully utilized because the volumetric capacity of the body 12is limited by the length of the floor 22 which has been kept constant.In particular, when performing steps 2-4 (FIGS. 3-10) of the presentinvention, the height HS (FIG. 6) of the front-to-rear plateau profileline 36 (which takes into account the length of the floor) is lower thanthe height HE (FIG. 4) of the side-to-side plateau profile line 28(which takes into account the height of the side walls 18 plus thesideboards 56). Thus, the side-to-side plateau profile line 28 (FIG. 4)must be lowered to correspond to the height HS of the front-to-rearplateau profile line 36 (FIG. 6), thereby limiting the effectiveness ofthe sideboards 56 with regard to increasing the volumetric carryingcapacity of the truck body 12.

The opposite is true if the truck body 12 is lengthened, such as byusing a tail extension 58, while the side walls 18 are kept at the sameheight such as shown in FIG. 17. Specifically, in such a case the heightof the side walls 18 limits the volumetric carrying capacity of thetruck body 12 because the height HE of the side-to-side plateau profileline 28 is lower than the height HS of the front-to-rear plateau profileline 36. This fact can be compensated some by lengthening the length ofthe final load plateau 38, however the typical problem with lengtheningthe final load plateau is that the center of gravity of the load model25 is shifted rearward which may create an out of balance conditionrelative to the truck that is carrying the truck body and in lengtheningthe rear of the truck body the ground clearance of the truck body whendumped may be below the minimum required by statutory guidelines.Typical statutory regulations require that when dumped the rear lowercorner of the truck body be no lower than the centerline of the axle ofthe truck on which the dump body is mounted. Otherwise, the height ofthe load plateau line has to be lowered in the front-to-rear profilethereby limiting the extra volumetric carrying capacity and limiting thelength of the tail extension 58.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. Recitation of ranges of values herein are merely intended toserve as a shorthand method of referring individually to each separatevalue falling within the range, unless otherwise indicated herein, andeach separate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein, isintended merely to better illuminate the invention and does not pose alimitation on the scope of the invention unless otherwise claimed. Nolanguage in the specification should be construed as indicating anynon-claimed element as essential to the practice of the invention.

Preferred embodiments for this invention are described herein, includingthe best mode known to the inventor for carrying out the invention. Ofcourse, variations of those preferred embodiments will become apparentto those of ordinary skill in the art upon reading the foregoingdescription. The inventor expects skilled artisans to employ suchvariations as appropriate, and the inventor intends for the invention tobe practiced otherwise than as specifically described herein.Accordingly, this invention includes all modifications and equivalentsof the subject matter recited in the claims appended hereto as permittedby applicable law. Moreover, any combination of the above-describedelements in all possible variations thereof is encompassed by theinvention unless otherwise indicated herein or otherwise clearlycontradicted by context.

1. A method for estimating the volumetric capacity of a truck bodyhaving a pair of side walls, a front wall and a floor, comprising thesteps of: (a) establishing a side-to-side profile of a generic loadmodel by extending a load side line upward at a predetermined materialangle of repose from the upper edge of each of the side walls of thetruck body to a peak; (b) replacing the peak of the generic load modelside-to-side profile with an side-to-side load plateau profile line of apredetermined width while maintaining the load side lines at thepredetermined material angle of repose; (c) establishing a front-to-rearprofile of a generic load model by extending a front load line upwardfrom the upper edge of the front wall of the truck body at thepredetermined material angle of repose and a rear load line upward fromat or near a rear edge of the floor of the truck body to a peak; (d)replacing the peak of the generic load model front-to-rear profile witha front-to-rear load plateau profile line of a predetermined lengthwhile maintaining the front and rear load lines at the predeterminedmaterial angle of repose; (e) adjusting the final height of the loadplateau profile line in the front-to-rear profile and side-to-sideprofile of the generic load to the lesser of the height of the loadplateau profile line in the side-to-side profile as produced in step (b)and the height of the load plateau profile line in the front-to-rearprofile as produced in step (d); (f) creating a top, profile of thegeneric load from the side-to-side and front-to-rear profiles of thegeneric load produced in step (e), the top profile of the generic loadhaving a polygonal-shaped load plateau; (g) adjusting the shape of theload plateau by defining a final outer boundary of the load plateau as adosed curve inscribed in the polygonal-shaped load plateau from step(f); (h) contouring the side load lines produced in step (a) and thefront and rear load lines produced in step (c) below the final outerboundary of the load plateau into a generally conically shaped surfacein which the sides of the conical shaped surface are still inclined atthe predetermined material angle of repose to form a finalthree-dimensional generic load model defined by the load plateau fromstep (g) and where the generally conical shaped surface intersects theside walls; front wall and floor of the truck body; and (i) calculatingthe volume of the final three-dimensional generic load model.
 2. Themethod of claim 1 wherein the predetermined width of the side-to-sideprofile of the load plateau line of step (b) equals the predeterminedlength of the front-to-rear profile of the load plateau line of step(d).
 3. The method of claim 2 wherein the predetermined width andpredetermined length equal 20% of the distance between the side walls ofthe truck body.
 4. The method of claim 1 wherein the predeterminedmaterial angle of repose is 26.6.degree.
 5. The method of claim 1wherein the step of contouring the side load lines and the front andrear load lines comprises the steps of extending a plurality of contourlines downward at the predetermined material angle of repose at equalangular intervals around the final outer boundary of the load plateauuntil the contour lines intersect the truck body, extending contactlines between the points where adjacent pairs of contour lines intersectthe truck body, and extending contour planes between each adjacent pairof the contour lines from the final boundary of the load plateau to therespective contact line.
 6. The method of claim 1 wherein the load sidelines in step (a) are extended upward from the upper inner edge of theside walls of the truck body.
 7. The method of claim 1 further includingthe step of selecting the predetermined material angle of repose.